Optical system transmittance calibration method based on optical fiber interconnection

Abstract

The invention relates to an optical system transmittance calibration method based on optical fiber interconnection, and belongs to the technical field of optical measurement, and the method comprises the steps: carrying out the optical fiber interconnection of a receiving telescope through a photon lead formed by an optical waveguide, and forming interference fringes based on the integrated interference of the photon waveguide; for a simulated long-distance target, interference fringes corresponding to the simulated long-distance target are obtained at different sampling positions; the angular radius of the target is obtained by testing the contrast of the interference fringes; and the actual size of the target is obtained by combining the obtained angular radius and a result obtained by distance measurement, and the transmittance calibration of the optical system is completed. The influence of stray light on the spectrum and phase measurement of the optical system can be effectively inhibited by using the optical fiber interconnection system, and the chromatographic measurement of the pupil can be realized by using the optical fiber interconnection system, namely, the alignment condition of the system pupil is tested according to the change of the light intensity at the edge.

Description

Technical Field

[0001] This invention relates to the field of optical measurement technology, and in particular to a method for calibrating the transmittance of an optical system based on fiber optic interconnection. Background Technology

[0002] The transmittance of an optical system can be characterized by the ratio of the outgoing light flux to the incident light flux of the system under test. It is an important performance indicator that marks the strength of the transmitted light radiation energy of the optical system and characterizes the quality of the optical system. Its value will affect the imaging signal-to-noise ratio.

[0003] Traditional methods for testing the transmittance of optical systems have the following drawbacks: stray light has a significant impact on the spectral and phase measurements of the optical system, leading to inaccurate transmittance testing.

[0004] Therefore, solving the above problems has become an urgent task. Summary of the Invention

[0005] In view of the fact that stray light has a significant impact on the spectral and phase measurements in existing optical system transmittance testing methods, resulting in inaccurate optical system transmittance testing, this invention proposes an optical system transmittance calibration method based on fiber optic interconnection.

[0006] A method for transmitting power calibration of an optical system based on fiber optic interconnects includes the following steps:

[0007] Optical waveguides are used to form photonic leads to interconnect receiving telescopes with optical fibers, and interference fringes are formed based on integrated interference of photonic waveguides.

[0008] For a simulated distant target, its corresponding interference fringes are obtained at different sampling positions;

[0009] The angular radius of the target is obtained by testing the contrast of the interference fringes;

[0010] By combining the obtained angular radius and distance measurements, the actual size of the target is determined, and the transmittance of the optical system is calibrated.

[0011] The beneficial effects of this invention are:

[0012] This invention utilizes an optical fiber interconnection system to effectively suppress the influence of stray light on the spectral and phase measurements of the optical system. At the same time, the optical fiber interconnection system can be used to perform tomographic measurements of the pupil, that is, to test the alignment of the system's pupil by measuring changes in light intensity at the edge. Attached Figure Description

[0013] Figure 1 This is a flowchart of the transmittance calibration method for an optical system based on fiber optic interconnection as described in an embodiment of the present invention;

[0014] Figure 2 This is a schematic diagram of an optical fiber bundle combiner.

[0015] Figure 3 The figure shows the results of the transmittance test. In the figure, (a)-(f) represent the focal plane light intensity at different wavelengths.

[0016] Figure 4 This is a schematic diagram of the pentaprism scanning sampling principle.

[0017] Figure 5 This is a schematic diagram showing the positions of the fiber optic array and the lens array;

[0018] Figure 6 This is a schematic diagram showing another location of the fiber optic array and lens array;

[0019] Figure 7 This is a schematic diagram of the system's optical path. Detailed Implementation

[0020] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings and preferred embodiments.

[0021] Taking a large-aperture survey telescope with a prime focus as an example, its prime focus component camera terminal has a built-in misaligned curvature sensor (which uses two detectors located in front of and behind the prime focus to simultaneously collect defocus images), and the light source illumination intensity is assumed to be unsaturated.

[0022] See Figures 1-7 In this embodiment, photonic leads formed by optical waveguides are first used to interconnect the receiving telescope with optical fibers, and interference fringes are formed based on photonic waveguide integrated interference. Photonic integrated interference can be implemented using a planetary interferometer. For simulating distant targets, the corresponding interference fringes are obtained at different sampling positions. For example, the sampling positions in different field-of-view directions can be adjusted using guide rails and a turntable, such as... Figure 2 As shown. By testing the contrast of the interference fringes, the angular radius of the target can be obtained. Combined with the obtained angular radius and the results of distance measurements, the actual size of the target can be determined, thus completing the transmittance calibration of the optical system. Figure 4 As shown, the focal point behind is for measurement, and then a pentaprism extends out a hole to scan and measure the pass rate of the test.

[0023] First, to ensure phase consistency and pupil alignment accuracy in multi-channel interferometry of fiber-optic interconnected optical systems, joint calibration of the fiber optic links and front-end optical trusses is required. A tunable laser and a standard light source are injected into the fiber combiner, and the contrast of the interference fringes generated by photonic waveguide integrated interference is used to monitor the optical path difference and polarization state consistency of each photonic lead in real time. During system downtime, a built-in standard plane mirror couples the fiber output end to the rear optical path of the optical truss, ensuring precise alignment of the reference beam transmitted through the fiber with the main optical path of the system, thus completing the rear optical path alignment and baseline zero-position calibration. Subsequently, the plane mirror's rotation direction is switched to guide the test beam output from the fiber to the front-end element of the parallel optical path. By analyzing the change in fiber array coupling efficiency with the field of view and the focal plane intensity distribution, combined with a tomographic sampling strategy, the attitude deviation of the front-end element and the pupil alignment state are inverted. Because the near-geometric beam output from the fiber waveguide has a very small aperture and a very large equivalent F-number, it can equivalently simulate the forward beam propagation path of a tens-meter-scale long-focal system, thereby achieving high-resolution pupil alignment in large-aperture telescope integrated testing. For accuracy traceability, a microlens array calibrated with a standard plane wave is inserted into the fiber optic interconnect measurement link to compare the light spot distribution on the pupil surface before and after calibration. Simultaneously, a fiber optic spectrometer is used to collect spectral data before and after incident on the optical elements. Differential analysis is used to invert the transmittance distribution in different regions of the element surface, constructing a data cube containing both spectral and spatial dimensions. Finally, the absolute spectral response of the entire system link is calibrated using a standard radiation source to ensure the metrological traceability of the transmittance measurement results.

[0024] Furthermore, the receiving telescope uses an optical fiber combiner to receive the input light source.

[0025] Furthermore, the receiving telescope changes the light output position by switching an optical switch.

[0026] In practical applications, the system can be solidified using multiple sub-apertures, and the angular radius of the target can be determined based on the interference contrast between different sub-apertures.

[0027] This invention employs a fiber optic interconnect architecture, dividing a standard light source into several stronger optical paths. The ends of these optical paths are then connected to optical lenses with smaller apertures. This allows multiple small lenses to replace a fiber optic system the same size as the optical components for measurement, improving the system's cost-effectiveness. Furthermore, using smaller lenses instead of large optical mirrors increases rigidity while reducing weight. Simultaneously, the aperture of the light-transmitting element can be easily adjusted, resulting in greater compatibility.

[0028] For different optical paths, after blocking or using fiber optic attenuators to attenuate different paths, a specific path is used for transmittance measurement.

[0029] During measurement, first measure the optical power in front of the incident element to ensure that the angle of incidence of the emission and the optical power is perpendicular to the incident angle. Then record the power value. Next, place the measuring instrument on the optical path after the system to be measured has been transmitted, and then record a light intensity value.

[0030] The transmittance at the corresponding point can be obtained by recording the two light intensity values.

[0031] Next, repeat the above steps to measure the transmittance of the entire surface point by point.

[0032] After two light sources are generated very close to each other through optical interconnection, a far-field light spot is formed, and the overall transmittance change can be measured based on the contrast of the emitted stripes.

[0033] Transmittance testing can effectively improve the measurement uniformity of the system. By standardizing light intensity and spectrum, the impact of various film systems and dust on the overall transmittance of the system can be effectively determined.

[0034] Fiber optic interconnect systems can effectively suppress the influence of stray light on spectral and phase measurements. Furthermore, they enable tomographic measurements of the pupils, allowing for testing the alignment of the pupils based on changes in light intensity at the edges. Specifically, after initial light intensity calibration, even with small positional shifts in light intensity, the intensity distribution changes with component tilt. Therefore, tomographic measurements of light intensity at different pupil positions using fiber optic interconnect systems yield multi-pupil alignment data, and the least squares method is used to obtain multi-pupil attitude information. Compared to spatial multiplexing using photonic lanterns, this avoids mode aliasing. After calibration, the pupil deviation measurement resolution is better than 4%, and the transmittance consistency measurement accuracy is better than 2%.

[0035] By using a lens array at the back end, in conjunction with optical fibers, once the front wavefront tilts, the angle of the subsequent fiber array changes. This Gaussian deviation causes variations in coupling efficiency, resulting in fluctuations in the optical field. The wavefront tilt is adjusted by controlling these fluctuations. When the wavefront tilt is relatively stable, transmittance is detected using the charge count.

[0036] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0037] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A transmittance calibration method for an optical system based on fiber optic interconnection, characterized in that, Includes the following steps: Optical waveguides are used to form photonic leads to interconnect receiving telescopes with optical fibers, and interference fringes are formed based on integrated interference of photonic waveguides. For a simulated distant target, its corresponding interference fringes are obtained at different sampling positions; The angular radius of the target is obtained by testing the contrast of the interference fringes; By combining the obtained angular radius and distance measurements, the actual size of the target is determined, and the transmittance of the optical system is calibrated.

2. The transmittance calibration method for an optical system based on fiber optic interconnection according to claim 1, characterized in that, The angular radius of the target is determined based on the interference contrast between different sub-apertures.

3. A transmittance calibration method for an optical system based on fiber optic interconnection according to claim 1 or 2, characterized in that, The sampling position in different field of view directions can be adjusted using guide rails and a turntable.

4. A transmittance calibration method for an optical system based on fiber optic interconnection according to claim 1 or 2, characterized in that, The receiving telescope uses an optical fiber combiner to receive the input light source.

5. A transmittance calibration method for an optical system based on fiber optic interconnection according to claim 1 or 2, characterized in that, The receiving telescope changes the light output position by switching an optical switch.

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